Process for improving the sun protection factor of cellulosic fibre material

ABSTRACT

A process for improving the sun protection factor (SPF) of cellulosic fibre materials and blends thereof, which comprises contacting said materials with at least one compound of the formula (1) according to claim  1.

The present invention relates to a process for improving the sunprotection factor (SPF) of cellulosic fibre materials and blendsthereof, which comprises treating the cellulosic fibre materials with atleast fluorescent whitening agent (FWA) and preferably additionally atleast one reactive UV absorber. The invention moreover relates to newfluorescent whitening agents useful for that process.

The skin-damaging effect of UV radiation is well known. Protection fromstrong sunlight is usually sought by applying a sun cream, a compositionthat contains a UV absorber, directly to the skin. In particularly sunnyregions, for example in Australia or America, however, the rate of skindamage due to UV radiation has recently been increasing dramatically.Accordingly, more attention is paid in these countries to protecting theskin from solar irradiation.

It has therefore been proposed that the skin should be protected notjust directly, but also to reduce the UV transmissibility of theclothing and also of other sun protection articles, such as awnings orparasols. Especially cellulosic fibre materials are at least partiallytransparent to UV radiation, so that the mere wearing of clothing doesnot offer adequate protection to the skin from damage due to UVradiation. A remedy is possible here by incorporating UV absorbersand/or FWA's into the fibre material.

However, hitherto the results achieved in respect of the protection fromUV radiation in the area of cellulosic fibre materials, in particulartextile materials have not been completely satisfactory and theretherefore continues to be a need for improving the sun protection factorof these materials. Despite the fact that this is a general problem, onespecific aspect has been found especially problematic. In the case ofcellulosic fibre materials treated with fluorescent whitening agents(FWA's), incorporation of UV absorbers has been found to result in lossof the whitening effect, thus leading to an undesirable yellowing of thefibres.

It has now been found that, surprisingly, a particular class offluorescent whitening agents, especially if applied together withspecific UV absorbers, not only provides excellent sun protectionfactors for cellulosic fibre materials in general, but also results inlittle or no observable reduction of the degrees of whiteness of theso-treated materials. Correspondingly, the present invention provides aprocess for improving the sun protection factor (SPF) of cellulosicfibre materials and blends thereof, which comprises contacting saidmaterials with at least one compound of formula

in which M is hydrogen, an alkali metal atom, ammonium or a cationformed from an amine;

-   -   R₁ and R₁′ independently of each other are hydrogen, hydroxy,        optionally substituted alkyl, 4-morpholinyl, —NH—R₃, —N(R₃)₂ or        —O—R₃, wherein R₃ is optionally substituted alkyl or optionally        substituted aryl,    -   R₂ is a group of formula        wherein X is —O— or —NH— and R₄ is C₁-C₄-alkyl which carries at        least one hydrophilic substituent    -   and R₂′ has the meaning of R₁ or R₂.

R₂ and R₂′ can have different meanings. Preferably, however, they areidentical.

According to the invention, alkyl radicals are to be understood as beinggenerally open-chain or branched alkyl radicals containing from 1 to 6carbon atoms, for example methyl, ethyl, n- or iso-propyl, n-, sec- ortert-butyl or n-hexyl, n-octyl. Cycloalkyl is preferably cyclopentyl orcyclohexyl.

R₃ as aryl is preferably independently of each other phenyl or naphthylwhich are unsubstituted or substituted e.g. by C₁-C₆-alkyl, C₁-C₆-alkoxyor a hydrophilic substituent.

In preferably used compounds of formula (1) R₁ and R₁′ are identical andespecially preferred is the use of a compound of formula (1), wherein R₁and R₁′ are each are hydrogen, hydroxy, optionally substituted alkyl,—NH—R₃, —N(R₃)₂ or —O—R₃, wherein R₃ is optionally substituted alkyl oroptionally substituted aryl.

Especially preferred meanings of R₁ and R₁′ are hydrogen, hydroxy,unsubstituted C₁-C₄-alkyl or C₁-C₄-hydroxyalkyl, 4-morpholinyl, —NH—R₃,—N(R₃)₂ or —O—R₃, wherein R₃ is unsubstituted C₁-C₄-alkyl orC₁-C₄-hydroxyalkyl or unsubstituted phenyl or phenyl substituted bysulfo, C₁-C₄-alkylsulfonyl or C₁-C₄-hydroxyalkylsulfonyl.

The hydrophilic substituent in the radical R₄ is preferably —OM, —COOMor SO₃M in which M is hydrogen, an alkali metal atom, ammonium or acation formed from an amine.

The quantities of compound (1) to be applied to the cellulosic materialaccording to the process of the invention may vary over a wide range.However, when used in amounts of between 0.001 and 2% by weight, basedon the weight of the fibre material, useful effects may be obtained.Preferably, however, the amount of the compound of formula (1) used isfrom 0.005 to 1% and especially from 0.01 to 0.5% by weight, based onthe weight of the fibre material.

Cellulosic fibre materials are to be understood as meaning, for example,the natural cellulose fibre, such as cotton, linen and hemp, and alsocellulose pulp and regenerated cellulose. The process of the inventionis also suitable for treating hydroxyl-containing fibres present inblend fabrics, for example, blends of cotton with polyester fibres orpolyamide fibres.

The fibre materials used have a density of between 30 and 200g/m²,preferably between 100 and 150 g/m², the porosity of the material lyingin the range of 0.1 to 3%, preferably 0.1 to 1.5%.

Preferably, the cellulosic fibre material used is cotton or a cottonblend.

The fibres mentioned may be present in various forms, for example, asstaple or yarns or as wovens or knits.

A further aspect of the invention, as previously mentioned, is toprovide excellent sun protection factors for cellulosic fibre materialsby the combined use of a fluorescent whitening agents of formula (1) anda UV absorber. Usually little or no observable reduction of the degreesof whiteness of the so-treated materials results.

For this purpose, application of the UV absorber may be performedbefore, during or after treatment of the material with the FWA offormula (1).

Any UV absorber suitable for cellulosic fibre materials may be appliedfor this purpose. The UV absorber used may be, e.g., ano-hydroxybenzophenone, an o-hydroxy-phenylbenzotriazole, a2-aryl-2H-benzotriazole, a salicylic acid ester, a substitutedacrylonitrile, a substituted acrylaminoethylene, a nitrilohydrazone,o-hydroxyaryl-1,3,5-triazine, a sulphonated 1,3,5-triazine or preferablyan oxalic anilide.

Preferably reactive UV absorbers are used and particularly preferred arethe UV absorbers described in the U.S. Pat. No. 5,700,295, especiallythe oxalic anilides.

Especially preferred as UV absorber are the compounds of formula:

whereby

-   -   L₁ and L₂ independently of each other are hydrogen, sulpho,        hydroxy, C₁-C₄-alkyl or C₁-C₁₂-alkoxy,    -   x and y independently of each other are 1, 2 or 3,    -   X₁ chloro oder fluoro and    -   X₂ a reactive radical of the formula        is, wherein Z is a fibre-reactive group and n is 2 or 3.

A fibre-reactive group is to be understood as meaning such a group whichis capable of reacting with the hydroxyl groups of the cellulosic fibreor with the amino groups of polyamide fibre materials to form covalentchemical bonds. Many such reactive groups are known, in particular fromthe chemistry of the so-called “reactive dyes”. However, within thescope of the present invention, preferred fibre-reactive groups Z arethose in which Z is a radical of the formula:—SO₂—Y′  (6),—SO₂NH—Y′  (7),—NHCO(CH₂)₃SO₂—Y′  (8),—CONH(CH₂)₂SO₂—Y′  (9) or—NHCO—Y′  (10),

Y′ representing vinyl, β-sulphatoethyl, β-thiosulphatoethyl,β-phosphatoethyl, β-acyloxyethyl or β-haloethyl, especially those inwhich Z is a radical of formula (6) and Y represents —CH₂CH₂OSO₃M, Mbeing as defined previously.

The application of the FWA's and also, when desired, the UV absorberscan take place by an exhaust or continuous process as well known fromthe literature for similarcompounds.

In the exhaust process the liquor ratio can be chosen within a widerange, for example, from 3:1 to 200:1, preferably from 10:1 to 40:1. Itis advantageous to operate at a temperature of 20 to 120° C., preferably40 to 110° C.

The fibre-reactive UV absorbers are applied advantageously in thepresence of acid-binding agents, for example, sodium hydroxide, sodiumcarbonate, sodium bicarbonate, sodium formate, potassium carbonate,sodium silicate, sodium trichloroacetate or sodium triphosphate, in thepresence or absence of neutral salts, for example, sodium sulphate orsodium chloride.

The quantities of the UV absorbers to be applied to the cellulosicmaterial according to the process of the invention may vary over a widerange. However, when used in amounts of between 0.005 and 1% by weight,based on the weight of the fibre material, useful effects may beobtained. Preferably, however, the amount of the compound of formula (1)used is from 0.01 to 0.5% by weight, based on the weight of the fibrematerial.

In the continuous process, the liquor add-on is advantageously 40-700,preferably 40-500, % by weight. The fibre material is then subjected toa heat treatment process to fix the applied FWA's and UV absorbers. Thisfixing can also be effected by the cold batching method.

The heat treatment preferably takes the form of a steaming process in asteamer with ordinary or superheated steam at a temperature of 98 to105° C. for, for example, 1-7, preferably 1-5 minutes. The fixing of theUV absorber by the cold batching process can be effected by storing theimpregnated and preferably rolled-up material at room temperature (15 to30° C.) for 3 to 24 hours, for example, the cold batching time beingknown to depend on the UV absorber.

On completion of the application process and fixation, the treatedmaterials are conventionally rinsed, soaped, for example, for 20 minutesat 90° C. with a solution containing 1 g/l. of calcined sodiumcarbonate, and dried.

The treatment bath may optionally contain other customary auxiliaries,for example, levelling, wetting deaerating and antifoaming agents,penetration accelerants or crease resisting agents.

The cellulose fibre materials treated by the process of the presentinvention possess high sun protection factors. The sun protection factoris defined as the ratio of the harmful dose of UV energy on protectedskin to the harmful dose of UV energy on unprotected skin. Accordingly,a sun protection factor is also a measure of the transmissivity of fibrematerials untreated and of those treated with FWA's and reactive UVabsorbers described in this invention.

The sun protection factor can be determined, for example, by the methoddescribed by B. L. Diffey and J.Robson in J.Soc.Cosmet.Chem., 40,127-133 (1989).

Some of the fluorescent whitening agents of formula (1) are known, thespecific compounds of formula (11), however, are new and are a furthersubject of the present invention. The invention thus also providescompounds of formula

in which M is hydrogen, an alkali metal atom, ammonium or a cationformed from an amine;

-   -   R₁ and R₁′ independently of each other are hydrogen, hydroxy,        optionally substituted alkyl, 4-morpholinyl, —NH—R₃, —N(R₃)₂ or        —O—R₃, wherein R₃ is optionally substituted alkyl or optionally        substituted aryl,    -   R₂ is a group of formula        wherein X is —O— or —NH— and R₄ is C₁-C₄-alkyl which carries at        least one hydrophilic substituent    -   and R₂′ has the meaning of R₁ or R₂    -   with the proviso that the compound of formula (1), wherein    -   R₁ and R₁′ are each hydroxyethylamino and    -   R₂ and R₂′ are each phenylamino which is substituted in        p-position with hydroxyethyl-aminocarbonyl is excluded.

The compounds of formula (1) can be prepared by known methods, e.g., byreacting, under known reaction conditions, cyanuric chloride,successively, in any desired sequence, with each of anaminostiibene-disulfonic acid and compounds capable of introducing thegroups R₁ , R₁′, R₂ and R₂′.

The compounds of formula (1) exhibit distinguished solubility In watercombined with good affinity to cellulosic fibre material and aqueousformulations containing these compounds have excellent storagestability.

Especially if applied together with a UV absorber they confer to thecellulosic material excellent sun protection and a high degree ofwhiteness.

The UV absorbers of formula (3) are known or may be prepared by knownmethods.

The examples which follow illustrate the invention; parts andpercentages are by weight unless otherwise stated.

EXAMPLE 1 Preparation of the Compound

1. Step

214 g water was added to a laboratory reaction flask, followed by 4 gsodium chloride. Contents of the reaction flask were chilled to 10° C.using an ice bath. To the reaction flask was added 15.6 g cyanuricchloride slowly in 10 minutes. After all of the cyanuric chloride wasadded, a white suspension was formed, pH of the flask contents was 3.10.

To the reaction flask, still at 10° C. was added 140 g of a 12%(wt./vol.9 solution of 4,4′-diaminiostiblene-2,2′-disulfonic acid sodiumsalt (DAS) over a 1 hour period. After the addition was complete, thereaction mixture was held for another 50 minutes. The pH increased to4.42. The pH was controlled between 3 and 4.5 during the reaction using2.77 g 20 % wt./vol. (17 % wt./wt.) sodium carbonate. Contents of theflask were light orange in color with the suspension having goodstirability. HPLC verified that the reaction was complete, 96-97%purity.

2. Step

In a laboratory flask was placed 60 g water and 4 g sodium chloride.Then 15.92 g 4-amino-N-(2-hydroxyethyl)-benzamide was added to form asuspension. The suspension was heated to 60° C. with stirring. After 15minutes the suspension dissolved with the pH being 8.5. The aqueoussuspension from the first reaction step, still at 16° C., was added tothe aqueous solution of the benzamide over a 30 minute period. After thefirst 100 mL added, a bright yellow suspension was formed and theagitation was increased to compensate for the viscosity increase. Thetemperature of the reaction flask was maintained at 60° C. and pH wascontrolled between 6.5-7.0 using 1 M sodium carbonate. When the additionwas complete, the reaction mixture was stirred for another 1 hour at 60°C. HPLC showed that the reaction was complete, 94-95 % purity.Temperature of the reaction mixture was increased to 90° C. Theviscosity of the reaction mixture increased and the pH dropped to 5.32.pH was adjusted with 1 M sodium carbonate to 6.0.

3. Step:

An aqueous solution was prepared by diluting 5.98 g ethanolamine with 15g water. The aqueous ethanolamine solution was added to the second stepreaction product, slowly over a 2 hour period at 90° C. pH wascontrolled between 7.5 and 8.0 by the addition of ethanolamine. Duringthe addition, two phases were present. After the addition ofethanolamine, the reaction mixture was held at 90° C. with stirring.25.2 g 32 % wt./wt. sodium hydroxide was used to make sure that the pHof the reaction mixture was maintained above 7.0. After 6.5 hours, HPLCIndicated that the reaction was complete, 93 % pure.

Still at 90° C., 8.4 g 37% wt./wt. HCl was added. The pH dropped from 7to 4.5 and precipitate formed in 5 minutes. After the addition of HCl,the reaction mixture was stirred for 30 minutes. Then the reactionmixture was filtered hot through a warmed funnel. The filter cake waswashed with water at 60° C., water at 40° C. and finally with water atroom temperature. The filtrate was tested for the presence of chloridewith sodium nitrate and then dried to constant weight. The product offormula (101) was obtained as a yellow in a yield of 95-98%:

EXAMPLES 2-6

Following the procedure of Example 1, the following compounds can beprepared:

Example R₁ and R₁′ R₂ and R₂′ 2

3

4

5

6

EXAMPLES 7 and 8

Following the procedure of Example 1, the following compounds can beprepared: Example R₁ and R₁′ R₂ R₂′ 7

8

EXAMPLE 9

Two samples each of 10 g. of a pre-washed cellulose fabric (cottoncretonne) are treated in an AHIBA® dyeing machine for 60 minutes at 95°C. at a liquor ratio of 1:20 in two different aqueous liquors.

A) 3.0 ml/l hydrogen peroxide 35%

-   -   2.0 ml/l sodium silicate 38° Bé    -   2.0 ml/l caustic soda 36° Bé    -   0.5 g/l ULTRAVON EL

B) The same liquor as in A), but containing additionally

-   -   0.012% compound of formula (101) according to Example 1.

The results are given in the following table: Example WG (Ganz)* SPFvalue** 9 A) 83 3.3 9 B) 222 23.7*Whiteness degree: according to Ganz**Sun Protection Factor (SPF): according to AS/NZS 4399:1996, Melbournesunlight (average of 4 measurements)The above results clearly demonstrate the substantial Improvement in sunprotection factor attained by the use of compound (101).

Example 10

If the procedure of Example 9 is repeated, but with samples of differentcellulose fabric (cotton poplin) the results of the following table areobtained. Example WG (Ganz)* SPF value** 10 A) 82 3.5 10 B) 220 46.7*Whiteness degree: according to Ganz**Sun Protection Factor (SPF): according to AS/NZS 4399:1996, Melbournesunlight (average of 4 measurements)The above results clearly demonstrate the substantial improvement in sunprotection factor attained by the use of compound (101).

Example 11

Two samples each of 10 g. of a pre-washed cellulose fabric (cottoncretonne or cotton poplin, respectively) are treated in an AHIBA® dyeingmachine for 60 minutes at 95° C. at a liquor ratio of 1:20 in an aqueousliquor containing: 3.0 ml/l hydrogen peroxide 35% 2.0 ml/l sodiumsilicate 38 °Bé 2.0 ml/l caustic soda 36 °Bé 0.5 g/l ULTRAVON ELThe samples are then treated for 10 minutes at 40° C. at a liquor ratioof 1:20 in a fresh bath containing 0.01% (relative to the weight of thefabric) of the compound of the formula

The temperature Is then raised to 95° C., g/l Glauber's salt (anhydr.)are added and the temperature is kept for 30 minutes. Then 10 g/l sodaash are added and after 20 minutes 0.2% (relative to the weight of thefabric) of the compound of the formula (101) according to example 1.After further 30 minutes at 95° C. the bath is cooled down, the fabricrinsed and dried. The results obtained are shown in the followingtable:of the following table are. Example Fabric WG (Ganz)* SPF value**11 A) Cotton-cretone 204 32.7 11 B) Cotton-Poplin 205 71.2*Whiteness degree: according to Ganz**Sun Protection Factor (SPF): according to AS/NZS 4399:1996, Melbournesunlight (average of 4 measurements)The above results clearly demonstrate the additional improvement(compared to examples 9 and 10) in sun protection factor attained by theadditional use of compound (102), whilst the degree of whiteness of thetreated fabrics is not dramatically reduced.

1. A process for improving the sun protection factor (SPF) of cellulosicfibre materials and blends thereof, which comprises contacting saidmaterials with at least one compound of the formula

in which M is hydrogen, an alkali metal atom, ammonium or a cationformed from an amine; R₁ and R₁′ independently of each other arehydrogen, hydroxy, optionally substituted alkyl, 4-morpholinyl, —NH—R₃,—N(R₃)₂ or —O—R₃, wherein R₃ is optionally substituted alkyl oroptionally substituted aryl, R₂ is a group of formula

wherein X is —O— or —NH— and R₄ is C₁-C₄-alkyl which carries at leastone hydrophilic substituent and R₂′ has the meaning of R₁ or R₂.
 2. Aprocess according to claim 1 wherein, in the compound of formula (1), R₁and R₁′ are identical.
 3. A process according to claim 1, wherein, inthe compound of formula (1), R₁ and R₁′ are hydrogen, hydroxy,optionally substituted alkyl, —NH—R₃, —N(R₃)₂ or —O—R₃, wherein R₃ isoptionally substituted alkyl or optionally substituted aryl.
 4. Aprocess according to claim 1, wherein, in the compound of formula (1),R₁ and R₁′ are hydrogen, hydroxy, unsubstituted C₁-C₄-alkyl orC₁-C₄-hydroxyalkyl, 4-morpholinyl, —NH—R₃, —N(R₃)₂ or —O—R₃, wherein R₃is unsubstituted C₁-C₄-alkyl or C₁-C₄-hydroxyalkyl unsubstituted phenylor phenyl substituted by sulfo,
 5. A process according to claim 1,wherein, in the compound of formula (1), the hydrophilic substituent inthe radical R₄ is —OM, —COOM or SO₃M in which M is hydrogen, an alkalimetal atom, ammonium or a cation formed from an amine.
 6. A processaccording to claim 1, wherein the fibre material is additionallycontacted with at least one UV absorber.
 7. A process according to claim1, wherein the fibre material is additionally contacted with at leastone UV absorber of the formula

whereby L₁ and L₂ independently of each other are hydrogen, sulpho,hydroxy, C₁-C₄-alkyl or C₁-C₁₂-alkoxy, x and y independently of eachother are 1, 2 or 3, X₁ is chloro or fluoro and X₂ is a reactive radicalof the formula

wherein Z is a fibre-reactive group and n is 2 or
 3. 8. A compound ofthe formula

in which M is hydrogen, an alkali metal atom, ammonium or a cationformed from an amine; R₁ and R₁′ independently of each other arehydrogen, hydroxy, optionally substituted alkyl, 4-morpholinyl, —NH—R₃,—N(R₃)₂ or —O—R₃, wherein R₃ is optionally substituted alkyl oroptionally substituted aryl, R₂ is a group of formula

wherein X is —O— or —NH— and R₄ is C₁-C₄-alkyl which carries at leastone hydrophilic substituent and R₂′ has the meaning of R₁ or R₂ with theproviso that the compound of formula (1), wherein R₁ and R₁′ are eachhydroxyethylamino and R₂ and R₂′ are each phenylamino which issubstituted in p-position with hydroxyethylaminocarbonyl is excluded. 9.A process according to claim 1, wherein the amount of the compound offormula (1) used is from 0.5 to 10% by weight, based on the weight ofthe fibre material.
 10. A process according to claim 1, wherein theamount of the compound of formula (1) used is from 0.005 to 1% byweight, based on the weight of the fibre material.
 11. A processaccording to claim 10, wherein the amount of the compound of formula (1)used is from 0.01 to 0.5% by weight, based on the weight of the fibrematerial.
 12. A process according to claim 1, wherein the cellulosicfibre materials used have a density of between 30 and 200 g/m².
 13. Aprocess according to claim 1, wherein the cellulosic fibre materialsused have a porosity of between 0.1 and 3%.
 14. A process according toclaim 1, wherein the cellulosic fibre material used is cotton or acotton blend.
 15. Cellulosic fibre material whenever treated accordingto a process according to claim 1.